/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    Rule.java
 *    Copyright (C) 2001 University of Waikato, Hamilton, New Zealand
 */

package weka.classifiers.rules;

import weka.core.Copyable;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.RevisionHandler;
import weka.core.WeightedInstancesHandler;

import java.io.Serializable;

/**
 * Abstract class of generic rule
 * 
 * @author Xin Xu (xx5@cs.waikato.ac.nz)
 * @version $Revision: 1.8 $
 */
public abstract class Rule implements WeightedInstancesHandler, Copyable,
		Serializable, RevisionHandler {

	/** for serialization */
	private static final long serialVersionUID = 8815687740470471229L;

	/**
	 * Get a shallow copy of this rule
	 * 
	 * @return the copy
	 */
	public Object copy() {
		return this;
	}

	/**
	 * Whether the instance covered by this rule
	 * 
	 * @param datum
	 *            the instance in question
	 * @return the boolean value indicating whether the instance is covered by
	 *         this rule
	 */
	public abstract boolean covers(Instance datum);

	/**
	 * Build this rule
	 * 
	 * @param data
	 *            the data used to build the rule
	 * @exception Exception
	 *                if rule cannot be built
	 */
	public abstract void grow(Instances data) throws Exception;

	/**
	 * Whether this rule has antecedents, i.e. whether it is a default rule
	 * 
	 * @return the boolean value indicating whether the rule has antecedents
	 */
	public abstract boolean hasAntds();

	/**
	 * Get the consequent of this rule, i.e. the predicted class
	 * 
	 * @return the consequent
	 */
	public abstract double getConsequent();

	/**
	 * The size of the rule. Could be number of antecedents in the case of
	 * conjunctive rule
	 * 
	 * @return the size of the rule
	 */
	public abstract double size();
}
